1. Field of the Invention
The present invention relates to a 3-dimensional animation generating apparatus, and more particularly to an apparatus which generates 3-dimensional animation using a computer, according to user instructions.
2. Description of the Related Art
In recent years, personal computers have been used to draw images in a 3-dimensional space. In generating images using this type of computer, the individual images which exist in the 3-dimensional spaced are known as objects. These include not only cube-shaped objects such as dice, but other objects of a variety of shapes. Objects can be, for example, a general rectangular parallelopiped having differing height, width, and depth, a sphere, a circular cylinder, or a cone. It is also possible to draw, for example, a robot or the like which is made up of a combination of these shapes. In addition, the orientation of such an object in a 3-dimensional space is determined in a basic coordinate system which is established beforehand in the computer, these coordinates being known as world coordinates.
When an object is moved a bit at a time, each position being displayed in sequence on a screen, the object appears as if it is moving. This method of expressing the movement of an object is known as animation. To achieve smooth-appearing motion, it is necessary to have at least approximately 30 static images per second.
However, it is difficult for a user to generate all the 3-dimensional animated images in sequence from the beginning to the end of a single animated sequence. Because of this difficulty, 3-dimensional animation generating apparatuses which use computers are devised so that it is sufficient for the user to generate a number of key static images (known as key frames) of the animated sequence. To achieve a smooth-appearing animation, the remaining images to be inserted between the key frames are automatically generated by the computer by means of interpolation processing.
An object of an animated picture can each be individually controlled by the user. In the case in which one shape is expressed by a number of objects, a parent-child relationship is established with respect to the group of objects. In this parent-child relationship, a given object is established as the parent, with other objects connected as children to that given object, this connection being called a link, the child objects connected to a parent object being handled together with the parent. Specifically, when the parent object moves, the child objects move simultaneously, and when the parent object rotates, the child objects rotate simultaneously, while maintaining their positional relationship to the parent.
In 3-dimensional animation, the case must also be considered in which parent-child related objects are continuously moved, this being expressed by a plurality of animated pictures. To achieve smooth movement of a parent-child related object between static images, interpolation processing is performed.
What follows is a description of a prior art 3-dimensional animation generating apparatus related to angle interpolation between key frames of an object, and interpolation between parent-child related objects.